1. Field of the Invention
This invention relates to the field of lanterns that use compressed-gas fuel. More specifically, it relates to lanterns that include a gas-flow baffle to create, in the vicinity of the baffle and a mantle used with the lantern, a region having a fuel/air mixture that can be easily ignited. Once this region is established, it is ignited with a spark.
2. Description of Related Art
Lanterns that use compressed-gas fuel have been available for some time. To operate this type of lantern, the user connects the lantern to a source of compressed gas, such as a tank of propane. For ease of discussion, the invention is explained below using propane gas as an example. It is to be understood, however, that other suitable gases (including butane and mixtures of gases) may be used instead. The user then opens a valve, which allows the fuel to flow through a burner assembly and into a mantle, which is porous.
Traditionally, these lanterns are lit manually by holding a lit match near the outside of the mantle. When the gas escapes through the mantle and reaches the flame from the match, the gas starts to burn, which causes the mantle to glow brightly.
Lighting match-lit lanterns, however, can be cumbersome and inconvenient, particularly when it is dark outside. This type of lantern also suffers from a number of other disadvantages, including the inability to light the lantern if the user forgets to bring along matches, or if the matches get wet. In addition, because the mantle is extremely fragile, there is a significant risk that the mantle will be accidentally broken by the match.
To alleviate some of the problems associated with match-lit lanterns, various mechanisms have been proposed and implemented. For example, the Coleman Company Inc. makes a propane lantern, Model 5154B700T, with an electronic ignition system.
FIG. 1 is a schematic representation of the major components of that lantern. To operate that lantern, the user turns control knob 18 which opens a fuel valve 19 and releases gas into the burner 11. The gas mixes with air in the burner 11 and the fuel/air mixture flows out of the gas outlet 13 and into the mantle 14, and begins to escape through the porous mantle. In addition to opening the valve 19, turning the control knob 18 also actuates a piezoelectric spark generator 17. This spark generator 17 causes a spark to jump from a first electrode 15 to a second electrode 16. The first electrode is shaped like a blade and is about 3 cm long, 5 mm high, and 1 mm thick. Because these electrodes are positioned close to the outside of the mantle 14, the spark will ignite the gas escaping from the mantle 14, which causes the mantle. to glow.
Lanterns with electronic ignitions are significantly more convenient than the match-lit lanterns described above. With existing electronic ignition lanterns, however, sometimes the spark fails to light the lantern, particularly when the lantern is cold. Although the inventor has not performed any experiments to verify the reason, it may be because the gas in the vicinity of the mantle is moving relatively fast and has very little turbulence, which makes it difficult to ignite with a spark.
When the lantern does not light, the user can adjust the position of the electrodes and try to light the lantern again. Alternatively, the user can light the lantern using a match. But using these backup procedures is inconvenient, and therefore defeats the main advantage of the automatic ignition lanterns.
U.S. Pat. No. 3,843,311 describes some of the difficulties of lighting a lantern by providing a spark outside of the mantle. It also describes a system which claims to improve the lighting operation by generating a spark inside the mantle. It is, however, relatively difficult to manufacture lanterns that create sparks inside the mantle.